Sediment ingestion by worms and the production of bio‐clays: a study of macrobiologically enhanced weathering and early diagenetic processes

• Published in: Sedimentology
• Main Authors: NEEDHAM, S. J., WORDEN, R. H., CUADROS, J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2006
• Subjects: Iceland
• Online Access: http://dx.doi.org/10.1111/j.1365-3091.2006.00781.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-3091.2006.00781.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-3091.2006.00781.x

Abstract The experiments reported here show that a range of early diagenetic clay minerals can develop within ingested sand in the guts of creatures at a rate that is at least 2 or 3 orders of magnitude greater than in an abiotic environment. Early diagenesis in marine environments may be strongly influenced by the occurrence of sediment ingestion and excretion by animals. Using a set of artificial marine experiments and the common lugworm Arenicola marina , it is shown that sediment ingestion by macrobiota represents a new way in which to precipitate clay minerals or ‘bio‐clays’. Significant quantities of clay minerals can be the product of biological interaction within sediment. Tanks were constructed with artificially layered sediment and natural seawater. The experiments were conducted at room temperature for a total duration of 9 months. The silicate material fed to the worms was an unweathered, and thus clay mineral‐free, basalt from Iceland. Less than 2 μ m fractions from original, control and faecal samples were periodically analysed using X‐ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Faecal casts underwent mineral alteration as denoted by loss of primary minerals, especially plagioclase. New minerals in faecal casts from the lugworms included, kaolinite, illite, quartz and possibly chlorite. Inorganic weathering of similar parent basalt would probably produce an identical mineral assemblage but many more times slowly than with the macrobiotic mechanism demonstrated here.